1. Field of the Invention
The present invention relates to devices for filtering and purifying water to make such water potable, and more particularly to a portable water filtering and purifying device for quickly and simply removing extremely small microbes or other disease causing elements and contaminants from such water.
2. Description of Related Art
Contaminated drinking water is one of the leading causes of health problems throughout the world. While such problems are encountered on a daily basis by millions throughout the world, particularly in less developed countries, ensuring the safety of a supply of water is also a problem for soldiers, hikers, international travelers and others. Various well known waterborne diseases are common in untreated water, caused by microbial agents including protozoan parasites that cause Giardiasis and Cyclosporasis, and Crytosporidium parvum, viruses such as the hepatitis A and other viruses, and bacterium such as E. coli, salmonella typhi which causes Typhoid fever, Vibrio cholerae, and shigella species. Symptoms include fever and diarrhea, rashes, cramps, jaundice, liver disease as well as other diseases, and while in many cases such ailments can be treated if attended to quickly if not treated can worsen and cause permanent serious conditions and often death, particularly in the young, elderly, and those having compromised immune systems.
In addition to untreated water, treated water supplies may also contain contaminants. While most cities and large towns in developed countries have large piped water systems for continually transporting relatively high quality treated water to users, such tap water is only safe to drink if it has been fully treated and disinfected, and if the water system is well operated and maintained. Bottled-water is also increasingly popular throughout the world, and although usually presumed to be safe by most users, may also be contaminated not only by microbial hazards such as those already mentioned above but also by any number of chemical and physical hazards. Possible chemical hazards include lead, arsenic and benzene, while physical hazards include glass chips and metal fragments.
Numerous portable devices for filtering and purifying water to provide a potable water supply from untreated sources such as lakes and streams, or improperly maintained piped water supplies, and other sources are found in the prior art. For example, known are straw-type devices wherein the user places his or her mouth over one end of an elongated casing and sucks inwardly in the same manner as with a conventional straw to cause water to pass across or through a filter in the device. A problem with such suction filtering and purifying devices, however, is that there is a practical limit to the pore size of the openings in the filter elements used, measured in microns, which pore size determines what size particles can pass through the filter. Although obviously the smaller the pore size, the more microbial and other contaminants are filtered from the water, if the pore size of the filter is made too small, it becomes impossible for the user to pass a meaningful amount of water through the filter and straw merely by sucking. For example, while a maximum pore size of 4.0 microns will filter out Giardia cysts, a maximum pore size of 0.2-microns is required to filter out bacteria, which generally have a size of between 0.2 and 10 microns. Viruses, which typically range in size from 0.0004 to 0.1 microns, are too small to be filtered out by most filters, but many viruses will attach themselves to a larger host bacteria, and these viruses can be removed by removing the host bacteria. Even where a pre-filter is used to filter out larger particles that would immediately clog the main filter, the smaller the pore size of the main filter, the more quickly it will become clogged and ineffective. Others types of filtering and purifying devices are known, but they are bulky and inconvenient to carry and use and thus are not truly portable.
The present inventors, recognizing the problems associated with existing portable water filtering and portable has now developed a water purification device that can be carried easily in a backpack, bag, or clothing pocket that can be used with filters having a pore size small enough to filter out some viruses, down to 1 micron, and thus ensures that virtually all contaminants are removed from the water. In addition, another problem with the water filters having small pore sizes is that they quickly become clogged with contaminants and materials that have been removed from the water. As a result, many of such filters must be replaced continually with a new, clean filter, since even if the filter is sterilized by dipping it in a bleach solution or the like to kill harmful parasites and the like, such contaminants although possibly no longer harmful if ingested nevertheless remain trapped in the filter cartridge. This is a problem, particularly in less wealthy countries wherein while persons having a filtering device can avail themselves to a supply of clean and potable water as long as the device contains a new filter, once the filter become clogged either the user must have a replacement filter available, which is expensive, impractical, and unlikely, or the device will be rendered useless. The present inventor has thus also conceived of an arrangement for removing such contaminants and materials from the filter device quickly and easily, thereby making the filter reusable and extending its life more or less indefinitely. Both of such improvements are provided by the present device which not only can pump or force supplies of water through filters having a smaller pore size than would be possible with a regular manual sucking action, but in addition said same pumping action can be used to force contaminants and other materials clogging the filter out of such filter so that the device is ready to be used again.
It has also been found that the present water filtering and purifying device may be specially adapted for use in filtering water contained in bottles such as standard 16 ounce plastic water bottles, as well as other types of bottles and liquid reservoirs such as canteens. In particular, the device may be modified so that it includes a cap that fits the water bottle with which it is to be used. Furthermore, in another embodiment after entering the device through a pre-filter having a small pore size, the water is then passed or forced through both a disinfecting agent and an activated carbon bed to provide complete purification.